Extract [O I] and O I lines from PZ cube

Library imports and data loading

Copied from the 02-01-Raman-Wings-IR-Source-C notebook:

Note, that we only have the coadded version of the Peter cube, so the seeing is a bit worse than in the sharp ESO cube

Use moments to extract the [O I] 6300 line

This looks like we clearly have UNDERsubtraction of the sky.

That is the simpplest explanmation for the velocity bending towards the blue at low intensity.

There is clearly a problem still with the fainter pixels. Witness the trend of sig with intensity. But theis is not so important for studying the brighter parts.

The other [O I] line: 6363

This time around, we will just work with the co-added cube

Use the same mask as we used for 6300

Other lines in the wav range: [S III] and Si II